


Homeostasis

by orithea



Series: The Time Traveller's Flatmate [4]
Category: Sherlock (TV)
Genre: Alternate Universe - Time Travel, Anatomy, Hand Jobs, M/M, Oral Sex, Time Travel, ah yes the old "let's study" routine
Language: English
Status: Completed
Published: 2013-07-01
Updated: 2013-07-01
Packaged: 2017-12-16 18:00:58
Rating: Explicit
Warnings: No Archive Warnings Apply
Chapters: 1
Words: 3,729
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/864968
Author URL: https://archiveofourown.org/users/orithea/pseuds/orithea
Summary: <blockquote class="userstuff">
              <p>
  <i>Homeostasis: the maintenance of equilibrium within a social group, person, etc.</i>
</p>
<p>The top three buttons of Sherlock’s shirt are undone, and John slips two fingers under the fabric, traces slowly from the suprasternal notch up the left side of Sherlock’s neck to just under his ear—“Carotid artery”—and back down—“jugular vein.” This really was meant to help him study, but John can remember running his mouth over Sherlock’s neck where his fingers just were, months ago, and he knows that he’s going to lose his self-control by the time this is over because he’ll never stop wanting to do it again.</p>
            </blockquote>





	Homeostasis

**Author's Note:**

  * Translation into Polski available: [Homeostaza](https://archiveofourown.org/works/7428025) by [tehanu](https://archiveofourown.org/users/tehanu/pseuds/tehanu)



> Happy (belated!) birthday to [Nadia](http://xpectopatronads.tumblr.com), who I will gladly write porn for any time.
> 
> Like most other things in the Time Traveller's Flatmate series, it will make the most sense if you've read the main work. If you aren't interested in reading that first, the basic facts are that Sherlock time travels involuntarily and ends up in different points of John's past, so they have a long shared history together.

_11 June 1994 (John is 19, Sherlock is 32)_

Something has been simmering between them all day.

First Sherlock is pounding on John’s bedroom door at half ten in the morning and it’s all he needs to have his flatmates investigating the sound and to find a naked, much older man demanding entrance to John’s bedroom (especially Mike, the nosiest of the lot, who can’t keep a secret to save his life), so he stumbles—reluctantly, very reluctantly in spite of all the pleasantness that lies on the other side of that door—out of bed to let him in.

And, yes, he is naked, trying to shield himself with his hands which is really not like Sherlock—

“There are people sleeping on your sofa.” Sherlock lets his hands fall as he closes the door. John doesn’t look, nor does he pointedly _not_ look either, as if to prove that there’s nothing uncomfortable about this anymore.

“That would explain the sudden modesty,” John says through a yawn. He tumbles back into his bed, cringing when the springs screech in protest.

Sherlock yanks the duvet out from beneath John and wraps it around himself. John scowls. “I need that—I’m going back to sleep.”

“Mm,” Sherlock says, unconcerned. He unceremoniously dumps a few items of dirty laundry out of John’s desk chair and settles into it, stretching his legs out to rest on John’s bed and pulling the duvet around himself more snugly. “But _I’m_ here.”

John grins. Only a little, in spite of himself. “You’ve a very high opinion of yourself.”

“It’s deserved.” And, well, John can’t really argue with that. “Sleeping in late, aren’t you?” Sherlock peers at the clock on John’s bedside table, its numbers glowing red in agreement, and raises a brow.

“I’m a growing boy”—Sherlock snorts, John glares—“who needs lots of sleep.”

“Or you spent too much time at the pub last night.”

“Maybe,” John says, because it’s true and they both know it. “I’ve got a rugby match later and I didn’t get enough sleep to feel up for it.”

“But there’s studying to do. You’ve got exams next week.”

“How—?”

Sherlock points over his shoulder, without turning to look, toward John’s tacked-up calendar.

John forgets sometimes, since they’re together so sporadically, that Sherlock sees everything. “Show-off,” he says fondly. “Still, an hour’s sleep won’t make a difference.” John pulls the sheet over himself and turns on his side facing away from Sherlock, who remains quiet, but John can just _feel_ him radiating disapproval all the same. It takes less than two minutes for John’s resolve to crumble and he sits back up in bed. “Fine,” he grumbles, “I’ll get up and study, but when I’m dead on my feet of exhaustion later, don’t think I won’t blame you.” Just to be contrary, he grabs the corner of the duvet that’s still wrapped around Sherlock and tugs hard, upsetting Sherlock’s balance. “Get dressed. You’re quizzing me.”

They spend the next several hours sitting together on the bed with John’s notes spread out across their laps. John heats up leftover pad thai for lunch; Sherlock declines his offer for a plate of his own but commandeers John’s chopsticks to pick out and devour all the shrimp. It’s the sort of thing that John ought to find intolerably annoying—he’d never let his other friends get away with it—but like so many of Sherlock’s habits, he just can’t.

When they take the Tube to Blackheath that afternoon it’s rammed—the first truly sunny Saturday in ages has everyone out, blustery though it is—and they have to stand most of the way. John’s kit bag keeps being jostled about so he moves in closer to Sherlock, close enough that they’re pressed thigh to thigh ( _hip to waist_ , John notes wryly, having given up hope that he’ll ever reach Sherlock’s height) and a bit more than that when the train curves too sharply. John tries not to think about it. They’re mates; that’s all.

It’s the summer and they’re just playing touch, but it’s the usual blokes, and they’ve always played well together. Everyone’s still in top form from the recent end of the regular season, and it makes for a fantastic match. John’s a winger—a damn good one because he’s fast and he’s fearless—and with every try he touches down, he can’t help but to find Sherlock’s face and flush with pleasure at the approval he finds there. Sherlock’s wearing jeans at least, not his usual suit, but John’s still unfailingly able to pick him out of the crowd of spectators, sitting alone and few rows back, out of the sun. He’s always played better with Sherlock watching, even when he was just a kid in junior leagues. Touch or not, he takes a few tumbles and gets an elbow to the ribs and the face more than once. By the end of the match, he’s grass-streaked, scraped, and bloodied here and there, and so full of adrenaline that he feels like he could keep going for days.

After the win, there’s a chorus of voices shouting for a victory celebration at the pub. It’s tradition, win or lose, to end up at the local closest to The Rec, but John’s not up for it today.  He knows Sherlock will hate being ignored while they pretend not to know each other to avoid the awkward explanations, and honestly... John hasn’t had his fill of him yet; he wants Sherlock to himself, wants to be able to have those Sherlock conversations that no one else can quite understand.

“C’mon, Johnny boy! We owe you a round or two!” Dave calls after him, but John just waves him off and trots to the stands.

Sherlock is leaning against a railing with that entirely too casual, I-could-be-a-model air he has that John envies. “Bored?”

“Hardly.” Sherlock inclines his head towards John and pushes off from the railing to stand straight. “Red and black suit you.”

“D’you mean my kit or my face?” John answers with a laugh, then stops abruptly and sucks in a sharp breath as Sherlock cups John’s chin with his hand and tilts it up. Sherlock’s thumb brushes over John’s lip where it’s been split and the look on his face isn’t quite the one that he wears when he’s examining something (someone— _John_ when he’s been brazen enough to ask for the attention), but it’s intense, and there’s something behind it that combines with that gentle touch to John’s face to make his pulse speed up and his skin feel too tight.

“Both.”

John pulls away from him. “The cheek’s the only thing that feels like it might bruise. Well, that and my ribs.” His tongue darts out, runs over his bottom lip, and he swears that he can taste the pass of Sherlock’s skin over his own.

“Some ice will fix that.”

“I _know_. Doctor in training, remember?”

Sherlock smirks. “Speaking of your training...”

Which is how that simmering _something_ between them erupts, back at the flat after John’s showered and rejoined Sherlock in his bedroom. Anatomy is John’s first subject examination, and while the terms are as familiar to John as his own name by this point, it can never hurt to review.

Sherlock is stretched out across John’s bed: arms out, palms up; long legs spread with his feet just hanging off the edge of the mattress. His eyes follow the movement of John’s hands.

“Right atrium, left atrium, left ventricle, right ventricle” John recites, tapping his finger counterclockwise over Sherlock’s heart to point out each in turn. “The blood enters the right atrium through the superior and inferior vena cava”—two fingers this time, tracing above and below to meet in the middle, and Sherlock squirms as the light touch tickles through his shirt—“to flow through the tricuspid valve and into the right ventricle. Pulmonary artery into the lungs, pulmonary vein back to the heart and into the left atrium. Through the mitral valve and into the left ventricle, then out into the body.”

The top three buttons of Sherlock’s shirt are undone, and John slips two fingers under the fabric, traces slowly from the suprasternal notch up the left side of Sherlock’s neck to just under his ear—“Carotid artery”—and back down—“jugular vein.” This really was meant to help him study, but John can remember running his mouth over Sherlock’s neck where his fingers just were, months ago, and he knows that he’s going to lose his self-control by the time this is over because he’ll never stop wanting to do it again.

John can see that Sherlock’s nipples are hard through the fabric of his shirt. He’s staring; his mouth feels dry and he licks his lips.

“Forget what comes next?” Sherlock asks. His voice is calm, unreadable, but there’s a flush on his cheekbones, creeping down his throat.

“No.” John’s hand is on the fabric of Sherlock’s shirt now, hovering above that first still-fastened button. “Thinking this would be easier without your shirt.” When Sherlock nods, John slips the buttons free easily—hands steady—and parts the fabric when he’s done. Sherlock sits up, holds out each wrist in turn for John to unfasten, then slips the shirt from his shoulders and tosses it aside before he lies back down.

John takes Sherlock’s left hand in his right and uses the fingers of his left hand to brush a path over skin. Between Sherlock’s pale complexion and vascularity, the veins are easy to find. “Radial, ulnar, median antebrachial veins, median cubital vein”—Sherlock’s arm tenses and when John looks up he sees that Sherlock’s nose has scrunched up in effort not to laugh or pull away from the ticklish travel of John’s fingers over the thin skin of his inner elbow—“basilic, cephalic, brachial...”

Sherlock sucks in a deep breath when John reaches the axilla.

“Touch too light?” John asks, teasing.

“ _Yes_ ,” Sherlock gasps out, and _fuck_ , John was not prepared for him to sound so serious, to have moved from playful to turned on just like that.

John doesn’t stop, doesn’t let himself think before doing, just tilts down and replaces his fingers with his mouth. Nips at the skin over Sherlock’s bicep just hard enough to make him gasp again and buck upwards, seeking; nudges his nose into Sherlock’s armpit just a bit and indulges in the smell of him (he misses it when Sherlock’s gone—sometimes delays washing his shirts so that he can pull them out and remember when there’s a long stretch between visits, remind himself that this impossible man _is_ real) before raising his head to announce, “Axillary vein”; places open-mouthed kisses along his shoulder before darting out his tongue to trace along Sherlock’s clavicle then speak against his skin, “Subclavian.”

Revisiting the path taken with his fingers: suprasternal notch to laryngeal prominence with his tongue; a detour to sink his teeth into the trapezius; trailing bites, licks, and suction along the side of Sherlock’s neck, over his pulse, and underneath his jaw.

“You covered that already,” Sherlock admonishes, then pulls John roughly into a kiss that leaves them both panting when it’s done. “And you skipped all of this.” He holds up his right hand; the left now resting at the small of John’s back.

“Didn’t skip it, just haven’t got back to it yet.” John pulls Sherlock’s hand towards him. “Dorsal arch,”—a kiss to the back of his hand—“palmar arch: deep and superficial,”—two kisses on the palm—“digital veins and arteries”—a kiss to the thumb and each four fingers, before sucking two of them into his mouth.

Sherlock’s breathing goes ragged and his eyes on John are incendiary. John smiles, self-satisfied, around his fingers and gives them one hard suck before pulling his mouth off. “Right, trousers off now would be best, I think.” He smiles again when Sherlock complies instantly.

Once Sherlock has settled back against the mattress, John moves to the foot of the bed and picks up Sherlock’s left leg, nudging a bit until Sherlock bends his knee and pulls it back towards his chest. “Digital, metatarsal, tarsal, plantar,” John recites, glossing over the fine details because neither of them really care about that any longer. When John rubs his thumb over the arch of Sherlock’s foot it makes Sherlock’s toes curl, and John smiles before placing a chaste kiss on his ankle. “Tibial, popliteal,” John says, and kisses Sherlock’s calf and the back of his knee before letting go of his leg and lowering himself to his stomach between Sherlock’s thighs. Sherlock spreads them to accommodate him, and John pushes them farther apart to hear the groan of want that he knows will come with it.

The muscles of Sherlock’s inner thighs are taut and trembling under John’s mouth as he works his way upwards, sucking bruises along the way. John gives up the pretense of the anatomy lesson altogether and announces nothing as he reaches Sherlock’s groin, noses against his erection, then pulls aside his pants to lick a long stripe of skin until he reaches the point where he could feel Sherlock’s femoral pulse against his tongue if he pressed hard enough to find it.

“ _John_.” Sherlock’s voice is wrecked and his hands fist into the sheets.

It’s been almost a year and a half since they first time they slept together, and it’s happened again nine times since—not every time that Sherlock visits, but most of them, until these past few months after John decided it possibly wasn’t the best idea he’s ever had to let it get started in the first place. Ten different encounters, mostly with their hands on each other, Sherlock’s mouth on him, and the last time—the time that made John decide that maybe this was too much after all—Sherlock had let John spread him open and press inside and it was perfect, fucking _perfect_. And, well, now that it seems this is back on again, John thinks he should try something new.

“I want to suck you,” John says, hooking his fingers in the elastic of Sherlock’s pants and giving a little tug. “Can I?”

“God. Please.” Sherlock is breathless. He lifts his hips to help as John works his briefs down.

“I haven’t before,” John admits. If they were normal Sherlock would know this. As it is, maybe they have done this before together, some other time that hasn’t even happened yet. John’s learned to stop thinking about it.

“Ah,” Sherlock says, more moan than word because John’s taken his cock in hand and given it a long, slow stroke. “I didn’t know—we have.” There’s that answered.

“Tell me,” John says, “if I do it wrong.” He ducks his head down, watches his hand move along Sherlock’s shaft, the way the foreskin slides back on the downstroke. John’s intimately familiar with the weight of Sherlock’s cock in his hand, how it feels rutting against his belly when they’re pressed together, but from this vantage point John finds it sort of intimidating, wonders how his mouth will stretch to fit. He’s never been tentative about trying anything new, though, and God knows his mouth on Sherlock’s skin is a familiar enough concept. He licks his lips and darts out his tongue to give a tentative lick to the underside, then pushes down until his lips close over it and his tongue pushes back Sherlock’s foreskin to swirl around the head.

The feedback from Sherlock is instant, a little jerk of his hips and a whispered “fuck” that makes pleasure burn inside of John’s belly, knowing that he pulled the rare expletive from him. Reassured, John swirls his tongue again, then sucks gently. He’s an adventurous boy, he’s tasted come before after it’s ended up smeared on his and Sherlock’s hands, and this isn’t terribly different. Sort of bitter, salty, and the slickness of it is surprising somehow. It’s—it’s a turn on, more than he thought it would be, having a cock in his mouth and his jaw stretching open, and he moans around it and sinks down a few more inches.

“ _Fuck_ ,” Sherlock says again, and when John raises his eyes to look at him he’s biting his lip, watching avidly as John pulls back and slides his mouth down again. “You’re good,” he pants, “so good.”

Emboldened by the praise, John takes in even more, which makes him gag and blow out his breath through his nose. He slides back off, coughs, and takes in a deep breath.

“It’s not how much you take in,” Sherlock says, “it’s the tongue and the suction.”

John wipes his mouth on the back of his hand. “And that was good?”

“I said so, didn’t I?”

That inspires a proud smirk, and John moves down to take him in again, sucks in long, slow pulls and slides his tongue along the underside of Sherlock’s cock. It has him trembling beneath him, and one hand flies to rest on John’s head—not pushing, just fingers running through his slightly shaggy hair almost like petting. It’s encouraging. John pulls off again, strokes his exceptionally spit-slick hand over Sherlock’s cock while he talks. “If I want to take in more, what should I do?”

“Oh,” Sherlock says, and for a moment John thinks he’s too distracted to give an answer. “Relax your throat,” he says at last, “it will tighten up and you have to just breathe and let it relax. And go slow.”

John nods. It sounds simple enough. This time when he sucks Sherlock’s cock into his mouth he works it a little deeper.

“Like that,” Sherlock says, and if he sounded wrecked before it’s nothing compared to this, soft and reverent. “Just slow, like that.” Sherlock’s hand is on John’s throat now, gentle, just resting there and feeling the muscles work. “Swallow a little.”

John does, and he’s rewarded with a bitten-off moan that makes him wonder exactly why he waited so long to try this. It’s amazing, provoking all of this from Sherlock just on the first try. John pulls back and sinks down in an irregular rhythm, never quite managing to get all of Sherlock’s cock down his throat—he didn’t really think he’d manage the first time, but he wanted to _try_ —but it seems to be enough, inexpert as it is.

“John, I’m—” Sherlock warns, and John can tell, can feel the insistent twitching against his tongue. He pulls off after the second pulse, wrinkling his nose at the way the taste fills his mouth even after swallowing, and watches the rest of the come—one, two, three more pulses, growing weaker each time—dribble down Sherlock’s cock and over his hand. And suddenly John’s aware—having been distracted for at least ten minutes by his focus on getting it right—that he’s desperately hard, straining where he’s still confined in his jeans. He pops the button, unzips his fly, and unceremoniously shoves jeans and pants down together, fumbling to get a hand—the one still covered in Sherlock’s come—on his own cock to squeeze and stroke.

“Hey!” John cries, frustrated, because he’s only gotten a few slick jerks of his cock before Sherlock’s apparently recovered and grabbed his hand to make him stop.

“You were brilliant,” Sherlock says, his voice a low growl next to John’s ear. “Do you really think I’m going to leave you to give yourself a quick wank?” He covers John’s mouth with his own, thrusts their tongues together into a filthy kiss rather than letting John answer.

Then he’s on his back, Sherlock hovering over top of him and pinning both wrists together over his head. “ _Sherlock_ ,” John whines, “Sherlock, you can’t just hold me—oh—” _Apparently he can_ , John’s mind insists, because Sherlock’s other hand is finally back on John, stroking him. It’s too slow because Sherlock is an absolute fucking tease when he’s already come, always is, but it feels exquisite all the same, and John’s surprised to find that he likes this, _really_ likes the way that Sherlock has his hands held so that John’s at his mercy and all that he can do is twist his hips and fight for more friction.

Sherlock stops moving his hand entirely, with a wicked grin on his face. “You bastard,” John growls, but then he laughs breathlessly because he realises what Sherlock’s game is and digs his heels in so that he can push his hips harder. It strains his thigh muscles to do it, but John’s wriggling slides his jeans farther down his legs so that he can spread his knees wider, gain more leverage, and fuck up into the tight circle of Sherlock’s hand. When he finally comes it’s explosive, wrenching a relieved groan and a repeated chorus of “fuck, fucking _Christ_ ” from John’s lips until the trembling aftershocks of his orgasm subside.

John’s shirt is left an unsalvageable mess, and he pulls it over his head, wipes off his belly, and passes it to Sherlock to do the same with the drying semen still slicked across his own stomach. He also kicks the rest of his clothing off, now too hot and sweaty to want it back on, and lies back on the bed. Sherlock is next to him, and the narrow mattress makes it necessary for him to turn on his side and throw a leg over John’s hip so that they both fit.

They’re quiet together for a while, and John feels himself drifting off to sleep when Sherlock says, “No need to thank me for my help.”

“What?” John doesn’t quite follow.

“With your studying,” Sherlock explains, then rolls his eyes when John looks at him blankly. “I don’t think you’ll be forgetting any of what you covered”—He waves a hand over his own skin, and if John weren’t feeling so sated and wonderfully relaxed he might just blush to remember it—“thanks to my help.”

“I think I demonstrated that I knew it all very well already, thanks.”

“Maybe. But that was some very positive reinforcement.”

John laughs. “Fine. But since you’ve appointed yourself saviour of my academic career, just remember that I have a good three more years to go.”

“Looking forward to it,” Sherlock says, and plants a kiss on John’s shoulder.


End file.
